Diet, exercise and brain training may help keep the mind 'sharp'

NHS Choices Behind the Headlines service exaimines the science behind recent claims that an active lifestyle and healthy diet can stave off dementia.

"Dancing, doing Sudoku and eating fish and fruit may be the way to stave off … mental decline," The Guardian reports. A Finnish study suggests a combination of a healthy diet, exercise and brain training may help stave off mental decline in the elderly.

The study looked at whether a combined programme of guidance on healthy eating, exercise, brain training and the management of risk factors such as high blood pressure (associated with vascular dementia) could have an effect on dementia risk and cognitive function.

Half of the 1,260 people in this two-year study were randomly allocated to receive this programme, while the other half acted as a control group, receiving only regular health advice. All participants were given standard tests to measure their brain function at the start, and at 12 and 24 months.

Researchers found that overall, scores measuring brain function in the group who received the programme were 25% higher than in the control group. For a part of the test called "executive functioning" (the brain's ability to organise and regulate thought processes), scores in the intervention group were 83% higher.

While the results of this well-conducted study are certainly encouraging, it's worth pointing out that the study does not look at whether people developed dementia in the longer term.

Where did the story come from?

The study was carried out by researchers from several institutes in Scandinavia, including the Karolinska Institutet in Sweden, the Finnish National Institute for Health and Welfare, and the University of Eastern Finland.

It was funded by a number of different academic centres, including the Academy of Finland, La Carita Foundation, Alzheimer Association, Alzheimer's Research and Prevention Foundation, Juho Vainio Foundation, Novo Nordisk Foundation, Finnish Social Insurance Institution, Ministry of Education and Culture, Salama bint Hamdan Al Nahyan Foundation, and Axa Research Fund, EVO grants, Swedish Research Council, Swedish Research Council for Health, Working Life, and Welfare and af Jochnick Foundation.

The study was published in the peer-reviewed medical journal The Lancet.

The study was widely covered in the UK media. Most coverage was fair, although many papers reported that the study showed how lifestyle interventions can reduce the risk of dementia. This was incorrect – the study looked only at cognitive performance in people at risk of dementia.

A study with a much longer follow-up would be required to see if the interventions used in the study were effective in preventing dementia.

Reports also tended to only concentrate on the lifestyle interventions in the study and not the medical management. One of the interventions involved doctors and nurses monitoring risk factors for dementia, such as blood pressure and body mass index (BMI), with advice where needed for people to get medication from their GP.

It is possible some people found to be at risk – because, for example, they had high blood pressure – were prescribed medication by a physician and it was this that led to the improvement in cognitive function.

What kind of research was this?

This was a double blind randomised controlled trial (RCT) looking at whether a comprehensive programme of healthy eating, exercise, brain training and management of risk factors could have an effect on mental function in older people at risk of dementia. An RCT is the best kind of study to find out whether an intervention is effective.

The researchers say previous observational studies have suggested a link between cognitive function in older people and factors such as diet, fitness and heart health.

They say their study is the first large RCT looking at an intensive programme addressing whether a combination of interventions might help prevent cognitive decline in elderly people at risk of dementia.

What did the research involve?

Older adults at risk of dementia were randomised to receive either an intervention that addressed their diet, exercise, cognitive training and cardiovascular risk monitoring, or general health advice. After two years, the participants were compared using a range of cognitive assessments.

Researchers recruited 1,260 people aged 60 to 77. To be eligible, participants had to have a dementia risk score of six points or higher. This is a validated score based on age, sex, education, blood pressure, body mass index (BMI), total blood cholesterol levels, and physical activity. The score ranges from 0 to15 points.

Participants also had to have average cognitive function of slightly lower than expected for their age. This was established by cognitive screening using validated tests.

Anyone with previously diagnosed or suspected dementia was excluded. People with other major disorders, such as major depression, cancer, or severe loss of vision or hearing, were also excluded.

Participants were randomly assigned either into the intervention group or to a control group.

All participants had their blood pressure, weight, BMI, and hip and waist circumference measured at the start of the study, and again at 6, 12 and 24 months.

All participants (control and intervention group) met the study physician at screening and at 24 months for a detailed medical history and physical examination.

At baseline, the study nurse gave all participants oral and written information and advice on healthy diet and physical, cognitive, and social activities beneficial for the management of cardiovascular risk factors and disability prevention.

Blood samples were collected four times during the study: at baseline and at 6, 12, and 24 months. Laboratory test results were mailed to all participants, together with general written information about the clinical significance of the measurements and advice to contact primary health care if needed.

The control group received regular health advice.

The intervention group additionally received an intensive programme comprising four interventions.

Diet

The diet advice was based on Finnish nutritional recommendations. This was tailored to individual participants, but generally included high consumption of fruit and vegetables, consumption of wholegrain cereals and low-fat milk and meat products, limiting sugar intake to less than 50g a day, use of vegetable margarine and rapeseed oil instead of butter, and at least two portions of fish a week.

Exercise

The physical exercise programme followed international guidelines. It consisted of individually tailored programmes for progressive muscle strength (one to three times a week) and aerobic exercise (two to five times a week), using activities preferred by each participant. Aerobic group exercise was also provided.

Cognitive training

There were group and individual sessions, which included advice on age-related cognitive changes, memory and reasoning strategies, and individual computer-based cognitive training, conducted in two periods of six months each.

Medical management

Management of metabolic and cardiovascular risk factors for dementia was based on national guidelines. This included regular meetings with the study nurse or doctor for measurements of blood pressure, weight and BMI, hip and waist circumference, physical examinations, and recommendations for lifestyle management. Study doctors did not prescribe medication, but recommended participants contact their own doctor if needed.

Participants underwent a cognitive assessment using standard neuropsychological tests called the neurological test battery (NTB) at baseline and at 12 and 24 months. The test measures factors such as executive functioning, processing speed and memory.

Researchers looked at any changes in people's cognitive performance over the course of the study, as measured by an NTB total score, with higher scores suggesting better performance.

They also looked at various scores on individual tests. They assessed participation in the intervention group with self reports at 12 and 24 months and recorded their attendance throughout the trial.

What were the basic results?

In total, 153 people (12%) dropped out of the trial.

People in the intervention group had 25% higher overall NTB scores after 24 months compared with the control group.

Improvement in other areas, such as executive function, was 83% higher in the intervention group, and 150% higher in processing speed. However, the intervention appeared to have no effect on people's memory.

Forty-six participants in the intervention group and six in the control group suffered side effects; the most common adverse event was musculoskeletal pain (32 individuals in the intervention versus none in the control group).

Self-reported adherence to the programme was high.

How did the researchers interpret the results?

The researchers say their findings support the effectiveness of a "multi-domain" approach for elderly people at risk of dementia. They will be investigating possible mechanisms whereby the intervention might affect brain function.

Conclusion

This RCT suggests a combination of advice on lifestyle, group activities, individual sessions and monitoring of risk factors appear to improve mental ability in elderly people at risk of dementia.

Whether it will have an effect on the development of dementia in such a population is uncertain, but the participants will be followed for at least seven years to determine whether the improved mental scores seen here are followed by reduced levels of dementia.

The trial was done in Finland and its results may not be applicable elsewhere, although the interventions included, such as diet and exercise, are similar to other countries' recommendations.

This study shows that a combined approach is beneficial. What is not clear is how active the clinical management of cardiovascular risk factors was in each group. Both groups were given health advice, but the intervention group were monitored more regularly for risk factors such as high blood pressure.

Though the study physicians did not prescribe medication, the participants were informed of results so they could seek advice from their GP. We do not know how many people in each group sought treatment for high blood pressure or cholesterol, and this could have affected the results.

All in all, it seems this study provides further evidence of the benefits of a healthy lifestyle.

A good rule is that what is good for the heart, such as regular exercise and a healthy diet, is also good for the brain. It may also be useful to regard your brain as a type of muscle. If you don't exercise it regularly, it may well weaken.

Not all cases of dementia are preventable, but there are steps you can take to reduce your risk.